Abradant driving head



Dec. 5, 1933. H. L MYERS 1,938,493

(ABRADANT DRIVING HEAD Filed Feb. 16, i933 By f1 llorney Patented Dec. 5, 1933 ABRADANT DRIVING HEAD Harry L. Myers, Toledo, Ohio, assigner to The American Floor Surfacing Machine Company, Toledo, Ohio, a corporation of Ohio Application February 16, 1933. Serial No. 657,091

6 Claims.

This invention relates to a new and improved abradant driving head expressly designed for useY on power driven abrasive surfacing machines.

In order that the practicability and transcendent structural refinements of the invention may be best understood I deem it important to point out at the outset of the description that the construction herein illustrated and claimed ispe- V culiarly adapted for use in conjunction with disk type surfacing conditioning machines of the style 'now manufactured and marketed by the American Floor Surfacing Machine Company, particularly the embodiments covered in my copending applications Serial Number 621,968, filed July ll, 1932, and 655,106 filed February 3, 1933.

It is of far reaching importance that an abradant supporting and driving head of the construction herein described and claimed be adapted for use in the perfection of the disk edging machine disclosed in the aforementioned copending application Serial No. 655,106, led February 3, 1933.

Persons conversant with these forms of machines Will readily perceive that where a slightly conoidal xedly tilted head is utilized, and where a restricted segmental portion of the abrasive disk is pressed into contact with the Work, the

marginal portion of the head, as a unit, must possess certain yieldable compensative properties.

It is therefore my primary aim to provide a disk type abrasive supporting and driving head whose central and major portion is substantially rigid and whose marginal or peripheral portion possesses requisite flexible and attraction properties,

whereby to minimize rupturing damage to either the abrasive sheet or the compressible facing of the metallic backing member or plate.

Stated more specifically I have evolved and produced a driving head characterized by a backing unit embodying a plate having a compressible rubber facing on one side wherein the plate is substantially rigid throughout its area, and wherein its perimeter and the corresponding portion of the facing isv relatively flexible in order to provide the requisite abradant action while at the same time affording adequate protection against damage to the parts due to the compensative or accommodation properties.

Briefly stated the improved structure is characterized by a substantially rigid backing plate faced on its Work side with a substantially annular rubber pad or cushion which affords the desired compressible and adhesive traction properties and wherein the marginal portions of the plate and facing are spaced apart to provide the requisite clearance space permitting the required flexible action of the marginal edge portion of the facing, together with an abrasive sheet or disk attached only at its center to the backing plate and detached entirely from the rubber facing.

Another feature is predicated upon the aforesaid assembly wherein reinforcing means is carried by the peripheral portion of the rubber facing to acquire the desired degree of rigidity and to serve in the additional capacity of a protector for the peripheral edge of said facing.

In the drawing:

Figure 1 is a top plan View of the structure as developed in accordance with the principles of the present invention illustrating the preferred embodiment.

Figure 2 is an edge elevational view of the construction illustrated in Figure 1.

Figure 3 is a bottom plan View.

Figure 4 is an enlarged sectional view taken approximately on the plane of the line 4 4 of Figure 1.

In the drawing the numeral 5 designates the motion transmitting shaft to which the head is attached. The head may be conveniently described as a unit 6 embodying a metal backing plate or disk 7 and an appropriately proportioned and shaped facing 8. The facing, in practice, is composed of rubber of appropriate thickness formed integral with the under side of the backing plate. At its center the backing plate is provided with a collar 9 keyed or otherwise rigidly secured to the shaft as indicated at 10. The central under side of the'plate is thickened somewhat as indicated at 11 and fashioned to form a retention socket to accommodate a cup-shaped washer 12, the washer being removably held in place by a retention bolt 13 and these features 12 and 13 serving as the sole means of securing the abradant disk or sheet 14 operatively, to the unit 6. Also as shown in Figure 4 the backing plate is slightly tapered in a radial direction and its marginal edge portion is rabbeted as indicated at 15 to define a projecting ange or lip 16. The corresponding marginal portion of the facing or pad 8 projects slightly beyond the feather edge of the flange 16. This projecting portion is beveled downwardly. Embedded in the rubber at this point is a correspondingly beveled metal band or ring 17 slightly less in width than the thickness of the rubber so as to expose the extreme peripheral edge portion 18 of the rubber. The metal band is primarily a reinforcing member but is also conspicuously important in that it functions as a protective guard for the marginal portion of the rubber facing in order that it may not be damaged or disrupted by protruding nails and obstructions on the adjacent surface of the work, wall, trim, washboard and the like. Not only does the ring 17 perform as a protective guard or rim, but it has a tendency to constrict and limit the compression of the immediately adjacent portion of the rubber to prevent it from flattening or distending to an objectionable degree when forced rmly down against the surface being acted on.

It will be noted in Figure 4 that the abrasive disk 14 has a central portion apertured and forced up into the cup like socket 19 to permit it to be firmly clamped in place in the manner illustrated. It is evident, of course, that the major portion of the abrasive disk is loose and not attached to the rubber facing 8. It is in this sense that the rubber facing provides the desired adhesive traction properties for effectively rotating the abrasive disk.

Needless to say the primary purpose of the groove or rabbet 15 and the overhanging flange 16 is to provide a clearance space between the reinforced edge portion of the rubber facing and the flange allowing said edge portion to attain the desired flexible and compressible result without undue spreading.

The gist of the invention is found-in the provision of a skilfully designed supporting and driving head for a sandpaper disk 14 wherein the disk is attached to the head at its center only, and wherein the head is characterized by a well balanced and appropriately strengthened unit 6 embodying the rigid backing disk or plate 7 and the compressible traction facing for pad 8. The paramount feature of the construction is predicated upon the rigid backing plate 7 and the marginal features 15, 16, 17 and 18, in that the latter features afford adequate propulsion for the adjacent portion of the disk 14 while at the same time allowing it to flex to compensate for irregularity occurring in the work surface and to thereby avoid breakage.

A careful consideration of the foregoing description in conjunction with the illustrative drawing will enable the reader to obtain a clear understanding of the purpose, features and advantages, the explicit construction, and the invention as hereinafter claimed.

It is to be understood that minor changes in shape, size, relative proportions, and materials may be resorted to in practice without departing from the spirit of the invention or the scope of the invention as now claimed. l

Having thus described my invention, what I claim as new is:

1. In a structure of the class described, in combination, a surface abrading sheet, a compressible and flexible member superimposed upon said sheet, a substantially rigid backing plate superimposed on said flexible member and attached thereto and constructed to permit flexing of the marginal portion of said member, and reinforcing means associated with the peripheral portion of said member tending to resist undue flexibility Aand spreading.

2. In a structure of the class described, in comblnation, a substantially rigid metal backing plate, a. compressible rubber pad attached to one face of said plate, the marginal portions of the pad and plate being spaced apart to permit a desired degree of flexibility at this point in the structure, and reinforcing means carried by the peripheral edge portion of said pad, said means having the additional function of a protective guard.

3. In a structure of the class described, a substantially rigid backing disk having the underside of its marginal portion rabbeted to provide an overhanglng flange, an annular compressible rubber facing secured to the underside of said disk having its marginal portions projecting beyond the corresponding portion of the disk and spaced from said :flange to permit flexing.

4. In a structure of the class described, a substantially rigid backing disk having the underside of its marginal portion rabbeted to provide an overhanging flange, an annular compressible rubber facing secured to the underside of said disk having its marginal portion projecting beyond the corresponding portion of the disk and spaced from said flange to permit flexing together with a marginal band surrounding the peripheral edge of said pad.

5. An abradant driving head comprising a rigid backing disc, coupling means carried by said disc adapted for connection to the drive shaft of an abrading machine, a pliant, adhesive traction disc secured to the underside of said backing disc and being of a diameter corresponding approximately to that of the backing disc, a metal reinforcing band anchored in the peripheral portion of the adhesive traction disc, the marginal portions of said discs being spaced apart to permit flexing of the traction disc toward and from corresponding part of the backing disc.

6. An abradant driving head of the class described comprlsing a backing plate and a compressible rubber pad attached to the driving face of said plate, the marginal portions of the pad and plate being spaced apart to permit the marginal portion of the pad to flex toward and from the corresponding portion of the plate, and a metal band surrounding the periphery of the pad to function as a protective guard and reinforcing means.

HARRY L. MYERS.

lSC 

